System and method for preventing robocall voicemail deposit

ABSTRACT

Systems and methods for preventing a robocall from leaving a voicemail are described. When an incoming call without a history information header (HIH) destined for a subscriber is detected, the incoming call is prevented from leaving a voicemail if the subscriber does not answer the incoming call. If the incoming call has the HIH, additional determination process based on a visited network address of the subscriber is performed to determine whether the incoming call is to be prevented from leaving a voicemail.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims priority to,co-pending, commonly-owned U.S. patent application Ser. No. 15/690,023filed on Aug. 29, 2017, which is incorporated herein in its entirety byreference.

BACKGROUND

Modern telecommunication systems include heterogeneous mixtures ofsecond, third, and fourth generation (2G, 3G, and 4G) cellular-wirelessaccess technologies, which can be cross-compatible and can operatecollectively to provide data communication services. Global Systems forMobile (GSM) is an example of 2G telecommunications technologies;Universal Mobile Telecommunications System (UMTS) is an example of 3Gtelecommunications technologies; and Long Term Evolution (LTE),including LTE Advanced, and Evolved High-Speed Packet Access (HSPA+) areexamples of 4G telecommunications technologies. The 5G telecommunicationtechnologies are the next generation mobile networks that are designedto combine both an evolution and revolution of the existing LTE/LTE-Amobile networks to provide a much higher connectivity, greaterthroughput, much lower latency, and ultra-high reliability to supportnew use cases and applications. Some of mobile devices operating in suchtelecommunication systems are also capable of operating over Wi-Finetworks for voice, also known as Voice-over-IP (VoIP) and data.

A user of such a mobile device may occasionally receive a call from anunknown caller, which may turn out be an unwanted call such as a sales,telemarketing, robocall, spam, and the like. Even if the user hadsubscribed to a caller ID service, seeing an unknown telephone numbermight not necessarily inform the user whether the call was an unwantedcall. The phone number provided by the caller ID service may even be aspoofed number by a scammer. If the user is out of coverage or isoutside of the user's network, for example, while roaming, and the callis rejected or unanswered, the call is directed to the user's voicemailsystem where the caller may leave a voicemail, which may be unwanted.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items or features.

FIG. 1 illustrates an example flow diagram of a normal voicemail depositprocess via call forwarding for a roaming subscriber.

FIG. 2 illustrates an example flow diagram for preventing a robocallvoicemail deposit.

FIG. 3 illustrates an example flow diagram for preventing a robocallvoicemail deposit when the HIH is present.

FIG. 4 illustrates an example flow diagram for preventing a robocallvoicemail deposit when the UE is determined to be roaming.

FIG. 5 illustrates an example process for preventing a robocallvoicemail deposit.

FIG. 6 illustrates an example process detailing one of the blocks ofFIG. 5.

FIG. 7 illustrates an example block diagram of a system for preventing arobocall voicemail deposit.

DETAILED DESCRIPTION

Systems and methods discussed herein are directed to a mechanism forpreventing unwanted voice deposits, such as voicemails for robocalls.

To determine whether to allow a caller of an unanswered call to leave avoicemail, a valid incoming call for an outbound roaming subscriberneeds to be distinguish from the unwanted call, such as a robocall and aspam call, for example, by evaluating presence of a history-info-header(HIH) in associated with the unanswered. The HIH captures anyredirection information that may have occurred on a particular call,such as a call for an outbound roaming subscriber who is a homesubscriber roaming outside of the subscriber's network. When theoutbound roaming subscriber is not able to accept an incoming call(i.e., the incoming call is rejected, unanswered, or the subscriber isout of coverage), the incoming call, now an unanswered call, isforwarded to the subscriber's voicemail system, where the caller of theunanswered call may leave a voicemail for the subscriber. However, ifthe HIH is not present, for example, in a SIP INVITE of the unansweredcall, the unanswered call is prevented from leaving a voicemail.

If the HIH is included in the SIP INVITE of the unanswered call, thenthe visited network address of the subscriber is evaluated next. If thevisited network address of the subscriber is not a Home Global TitleAddress, indicating that the subscriber is roaming, but if thesubscriber is actually in the home network, then the unanswered call isprevented from leaving a voicemail.

The unanswered call may additionally be subjected to a challenge, wherethe caller of the unanswered call is asked to reenter a sequence ofrandomly generated number announced by the voicemail system. If thecaller fails to reenter the sequence correctly, the unanswered call isprevented from leaving a voicemail.

FIG. 1 illustrates an example flow diagram 100 of a normal voicemaildeposit process via call forwarding for a subscriber, more specificallya UE 102 of the subscriber, while roaming. A visited mobile switchingcenter (MSC) or a telephony application server (TAS) 104, forwards acall to the UE 102 at 106. If the UE 102 rejects the call, or the callis unanswered, the unanswered call is forwarded to a voicemail system ofthe UE as illustrated in 108. At 110, the visited MSC/TAS 104 sends aSIP INVITE 112 having a request uniform resource identifier (R-URI),which has voicemail (VM) pilot information, such as a telephone numberfor the VM, and the HIH, to a visited network session boarder controller(SBC) 114. The visited network SBC 114 then forwards the SIP INVITE 112,at 116, to a home network SBC 118. The home network SBC 118 thenforwards the SIP INVITE 112, at 120, to a Core Network 122, which maycomprise an MSC, a telephony application server (TAS), and a voicemail(VM) system where the caller may deposit a voicemail for the subscriber.The SIP INVITE 112 messages sent at 110, 116, and 120 may not beidentical to each other, however, they all include the same R-URI havingthe VM pilot information and the identical HIH.

FIG. 2 illustrates an example flow diagram 200 for preventing a robocallvoicemail deposit. As a result of the incoming call to the UE 102 beingunanswered, a SIP PEER 202, which may be an interface to the visitednetwork SBC 114 of FIG. 1, may forward the SIP INVITE 112 to an SBC,such as the home network SBC 118 at 204. The SBC 118, at 206, may relaythe SIP INVITE 112 and/or send a RESTful, or similar protocol, query toa verification function 208. In response to receiving the SIP INVITE112, the verification function 208 may check whether the R-URI is thevoicemail pilot and that the HIH is present in the SIP INVITE 112. Theverification function 208 may then transmit an inquiry 212 such as asend routing information (SRI) or an SRI to short message (SRI-SM) for ahome location register (HLR) 214, or a Diameter message for a homesubscriber server (HSS) 216. The HLR 214/HSS 216, in response toreceiving the inquiry 212 may return a response 218 including visitednetwork address information of the UE 102 to the verification function208 at 220. The HLR 214/HSS 216 may be, or may be a component of, aunified subscriber database (USD) (not shown).

If the R-URI is a valid voicemail pilot but the HIH is invalid or notpresent, then the unanswered call is presumed to be suspicious forlacking redirection information, and the verification function 208 maysend to the SBC 118 an error message 222 at 224. The error message 222may be a SIP Error code or a RESTful response to terminate theunanswered call. The SBC 118 may send to the SIP PEER 202 a SIP message226 to terminate the unanswered call at 228. The SIP message 226 may bea SIP 486 (user busy), SIP 403 (forbidden), or any other negative SIPresponse to terminate the unanswered call.

FIG. 3 illustrates an example flow diagram 300 for preventing a robocallvoicemail deposit when the HIH is present. Continuing from FIG. 2, basedon the visited network address information of UE 102 in the response218, the verification function 208 may determine whether the UE 102 ishome or roaming at 302. The verification function 208 may determine thatthe UE 102 is roaming if a visited network address of the UE 102 is anon-home global title address of the UE 102 in the response 218.

Upon determining that the UE 102 is in its home network, theverification function 208 may send the error message 222 at 304 to theSBC 118 to terminate the unanswered call, and the SBC 118 may send tothe SIP PEER 202 the SIP message 226 to terminate the unanswered call at306.

FIG. 4 illustrates an example flow diagram 400 for preventing a robocallvoicemail deposit when the UE 102 is determined to be roaming.Continuing from FIG. 3, upon determining that the UE 102 is roaming, theverification function 208 may send a permission message 402 at 404 tothe SBC 118. The permission message 402 may be a SIP or RESTful responsepermitting the unanswered call to deposit a voicemail. The SBC 118 thenmay send a SIP INVITE 406 at 408 to the core network 122, which includesa voicemail system, where the unanswered call may be permitted todeposit a voicemail for the UE 102.

Alternatively, the unanswered call may be subjected to anotherverification step before being permitted to deposit a voicemail. Afterreceiving the permission message 402, the SBC 118 may send the SIPINVITE 406 to a randomizer 410 at 412. The randomizer 410 may present achallenge to the unanswered call, or more specifically, to a caller ofthe unanswered call, to determine if the unanswered call is a robocallor a legitimate call. The caller may be requested to enter a sequence ofnumbers, which may be randomly generated and announced to the caller. Ifthe sequence of numbers is correctly entered, then the SIP INVITE 406 isforwarded to the core network 122 at 414 where the unanswered call isallowed to deposit a voicemail for the UE 102. If the sequence ofnumbers were not correctly entered, then the randomizer 410 may send theerror message 222 at 416 to the SBC 118 to terminate the unansweredcall, and the SBC 118 may send to the SIP PEER 202 the SIP message 226to terminate the unanswered call at 418.

FIG. 5 illustrates an example process 500 for preventing a robocallvoicemail deposit.

In block 502, an incoming call targeted to a UE, such as the UE 102, isrejected or otherwise unanswered. In block 504, the unanswered incomingcall, now referred as the unanswered call, may then be directed to avoicemail system, which may be a component of a core network of the UE102, such as the core network 122. In block 506, whether the R-URI hasthe voicemail pilot information may be determined. If the R-URI isdetermined not to have the voicemail pilot information in block 506, theunanswered call is processed normally in block 508. If the R-URI isdetermined to have the voicemail pilot information in block 506, thenwhether call redirection history information is present in an attributeof the unanswered call may be determined in block 510. The callredirection history information may be an HIH as described above thatincludes any redirection information that may have occurred on theunanswered call, and the attribute of the unanswered call may be a SIPINVITE associated with the unanswered call initiated in an InternetProtocol (IP) multimedia subsystem (IMS). A normal forwarded call shouldhave the HIH generated by a network node such as an MSC/MSS, if a legacycircuit-switched call, or a TAS, if an IMS call. If the HIH weredetermined to be invalid or not present in block 510, then theunanswered call may be prevented from depositing a voicemail in block512. If the HIH were determined to be valid and present in block 510,then the unanswered call may be further evaluated in block 514 beforebeing allowed to, or prevented from, depositing a voicemail.

FIG. 6 illustrates an example process 600 detailing further evaluationprocess of block 514 of FIG. 5. In block 602, whether a visited networkaddress of the UE 102 is a home global title address of the UE 102 maybe determined. The visited network address of the UE 102 may bedetermined by initiating an inquiry, such as a send routing information(SRI) or an SRI for short message (SRI-SM), to one of a home locationregister (HLR), a home subscriber server (HSS), or a unified subscriberdatabase (USD) of the home network of the UE 102.

If the visited network address of the UE 102 is determined to be thehome global title address of the UE 102 in block 602, then the UE 102may be presumed to be in the home network of the UE 102 in block 604,and the unanswered call may be prevented from depositing a voicemail inblock 606. If the visited network address of the UE 102 is determinednot to be the home global title address of the UE 102 in block 602, thenthe UE 102 may be presumed to be outbound roaming, i.e. not in the homenetwork of the UE 102, and the unanswered call may be allowed to deposita voicemail for the UE 102 in block 608.

Alternatively, the unanswered call may be subjected to a furtherchallenge before being permitted to deposit a voicemail. In block 610,the unanswered call, specifically a caller of the unanswered call, maybe requested to enter a sequence of numbers, which may be randomlygenerated and announced to the caller. If the sequence of numbers werecorrectly entered in block 612, then the unanswered call is allowed todeposit a voicemail for the UE 102 in block 608. If the sequence ofnumbers were not correctly entered in block 612, then the unansweredcall is prevented from depositing a voicemail for the UE 102 in block606.

FIG. 7 illustrates an example block diagram of a system 700 forpreventing a robocall voicemail deposit.

The system 700 may comprise one or more processors 702 and memory 704communicatively coupled to the one or more processors 702. The memory704 may comprise a plurality of modules that are communicatively coupledto each other. The plurality of modules may comprise a determinationmodule 706 that is configured to determine whether call redirectionhistory information is present in an attribute of the unanswered call,and a prevention module 708 that is configured to prevent the unansweredcall from depositing a voicemail if the call redirection historyinformation is not present in the attribute. The attribute of theunanswered call may a SIP INVITE, and the call redirection historyinformation may be a history-info header (HIH) included in the SIPINVITE. The HIH may generated by a network node in the core network 122such as a mobile switching center (MSC), a MSC server (MSS), or atelephony application server (TAS) as discussed above with referenced toFIG. 1.

The determination module 706 may be further configured to determinewhether a visitor location register visited network address of the UE102 is a home global title address of the UE 102. If the determinationmodule 706 determines that the UE 102 is in its home network the visitednetwork address of the UE 102, the prevention module 708 may prevent theunanswered call from depositing a voicemail. The determination module708 may determine the visited network address of the UE 102 is the homeglobal title address of the subscriber by initiating an inquiry to oneof a home location register (HLR), a home subscriber server (HSS), or aunified subscriber database (USD). The inquiry may include at least oneof a send routing information (SRI) or an SRI for short message(SRI-SM).

The memory 704 may further comprise a randomizer module 710 configuredto provide another verification step for the unanswered call. Todetermine if the unanswered call is a robocall or an automated call thathas no human associated with it, the randomizer module 710 may announcea sequence of numbers, which may be randomly generated, to the anunanswered call, or more specifically to a caller of the unanswered callwho may or may not be present. The randomizer module 710 may thenrequest the caller to enter a sequence of numbers from the announced setof numbers. If the caller fails to enter the sequence of numberscorrectly, the randomizer module 710 may prevent the unanswered call, orthe caller, from depositing a voicemail.

Some or all operations of the methods described above can be performedby execution of computer-readable instructions stored on a computerstorage medium, as defined below. The term “computer-readableinstructions” as used in the description and claims, include routines,applications, application modules, program modules, programs,components, data structures, algorithms, and the like. Computer-readableinstructions can be implemented on various system configurations,including single-processor or multiprocessor systems, minicomputers,mainframe computers, personal computers, hand-held computing devices,microprocessor-based, programmable consumer electronics, combinationsthereof, and the like.

The computer storage media may include volatile memory (such as randomaccess memory (RAM)) and/or non-volatile memory (such as read-onlymemory (ROM), flash memory, etc.). The computer storage media may alsoinclude additional removable storage and/or non-removable storageincluding, but not limited to, flash memory, magnetic storage, opticalstorage, and/or tape storage that may provide non-volatile storage ofcomputer-readable instructions, data structures, program modules, andthe like.

A non-transient computer storage medium is an example ofcomputer-readable media. Computer-readable media includes at least twotypes of computer-readable media, namely computer storage media andcommunications media. Computer storage media includes volatile andnon-volatile, removable and non-removable media implemented in anyprocess or technology for storage of information such ascomputer-readable instructions, data structures, program modules, orother data. Computer storage media includes, but is not limited to,phase change memory (PRAM), static random-access memory (SRAM), dynamicrandom-access memory (DRAM), other types of random-access memory (RAM),read-only memory (ROM), electrically erasable programmable read-onlymemory (EEPROM), flash memory or other memory technology, compact diskread-only memory (CD-ROM), digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices, or any other non-transmissionmedium that can be used to store information for access by a computingdevice. In contrast, communication media may embody computer-readableinstructions, data structures, program modules, or other data in amodulated data signal, such as a carrier wave, or other transmissionmechanism. As defined herein, computer storage media do not includecommunication media.

The computer-readable instructions stored on one or more non-transitorycomputer storage media that, when executed by one or more processors,may perform operations described above with reference to FIGS. 1-7.Generally, computer-readable instructions include routines, programs,objects, components, data structures, and the like that performparticular functions or implement particular abstract data types. Theorder in which the operations are described is not intended to beconstrued as a limitation, and any number of the described operationscan be combined in any order and/or in parallel to implement theprocesses.

CONCLUSION

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described. Rather,the specific features and acts are disclosed as exemplary forms ofimplementing the claims.

What is claimed is:
 1. A method for processing an unanswered call, themethod comprising: receiving the unanswered call at a voicemail systemassociated with a user equipment (UE); receiving, by the voicemailsystem, a voicemail pilot associated with the unanswered call;determining, by the voicemail system, that a call redirection history isabsent from the voicemail pilot; and preventing the unanswered call fromdepositing a voicemail with the voicemail system based at least in parton the voicemail pilot not including the call redirection history. 2.The method of claim 1, wherein: the voicemail pilot is a R-URI includedin a SIP INVITE of the unanswered call; and the call redirection historyis a history-info header (HIH) included in the SIP INVITE and R-URI, theHIH generated by a network node comprising at least one of a mobileswitching center (MSC), a MSC server (MSS), or a telephony applicationserver (TAS).
 3. The method of claim 1, further comprising: determiningthat the call redirection history is included in the voicemail pilot;determining that the UE associated with the voicemail system is in ahome network; determining that the call redirection history containsinformation indicating the UE is in a different network; and preventingthe unanswered call from depositing the voicemail with the voicemailsystem.
 4. The method of claim 3, wherein determining that the UEassociated with the voicemail system is in a home network comprises:identifying a home global title address of the UE; and determining avisited network address associated with the UE is the home global titleaddress.
 5. The method of claim 3, wherein determining that the callredirection history contains information indicating the UE is in adifferent network comprises: identifying a visited network address fromthe call redirection history; initiating an inquiry to one of: a homelocation register (HLR); a home subscriber server (HSS); or a unifiedsubscriber database (USD); and determining the visited network addressis not associated with the home network.
 6. The method of claim 5,wherein the inquiry includes at least one of a send routing information(SRI) or an SRI for short message (SRI-SM).
 7. The method of claim 1,wherein preventing the unanswered call from depositing the voicemailwith the voicemail system is based at least in part on: announcing a setof numbers to a caller of the unanswered call; requesting the caller toenter a sequence of numbers from the set of numbers; and determiningthat the caller failed to enter the sequence of numbers correctly.
 8. Anon-transitory computer storage medium storing computer-readableinstructions executable by a computer, that when executed by thecomputer, cause the computer to perform operations comprising: receivingan unanswered call, the unanswered call forwarded from a user equipment(UE); receiving an attempt to deposit a voicemail with a voicemailsystem, the attempt associated with the unanswered call and thevoicemail system associated with the user equipment; and preventing theunanswered call from depositing a voicemail based on at least one of:determining the attempt does not contain a call redirection history;determining the attempt contains an invalid call redirection history; ordetermining the attempt includes a first network address not associatedwith a network of the UE.
 9. The non-transitory computer storage mediumof claim 8, wherein: the attempt is a SIP INVITE; and the callredirection history is a history-info header (HIH) included in the SIPINVITE, the HIH generated by a network node comprising at least one of amobile switching center (MSC), a MSC server (MSS), or a telephonyapplication server (TAS).
 10. The non-transitory computer storage mediumof claim 8, wherein determining the attempt includes the first networkaddress not associated with a network of the UE further comprises:determining the first network address is a visited network address;determining that the visited network address is different from a homeglobal title address associated with the UE; and determining the networkis a home network of the UE.
 11. The non-transitory computer storagemedium of claim 10, wherein determining the visited network address isdifferent from the home global title address associated with the UEcomprises: initiating an inquiry to one of: a home location register(HLR); a home subscriber server (HSS); and a unified subscriber database(USD).
 12. The non-transitory computer storage medium of claim 11,wherein the inquiry includes at least one of a send routing information(SRI) or an SRI for short message (SRI-SM).
 13. The non-transitorycomputer storage medium of claim 8, wherein preventing the unansweredcall from depositing a voicemail is based at least in part on:announcing a set of numbers to a caller of the unanswered call;requesting the caller to enter a sequence of numbers from the announcedset of numbers; and determining that the caller failed to enter thesequence of numbers correctly.
 14. The non-transitory computer storagemedium of claim 13, wherein the set of numbers is randomly generated.15. A system configured to determine whether an unanswered call to auser equipment (UE) permitted to deposit a voicemail, the systemcomprising: one or more processors; memory communicatively coupled tothe one or more processors, the memory comprising a plurality of modulescommunicatively coupled to each other, the plurality of modulescomprising: a communication module configured to receive at least anattribute and a connection attempt associated with the unanswered call;a determination module configured to determine whether call redirectionhistory information is present in the attribute; and a prevention moduleconfigured to prevent the unanswered call from depositing a voicemailupon determining, by the determination module, that the call redirectionhistory information is not present.
 16. The system of claim 15, wherein:the attribute is a SIP INVITE; and the call redirection historyinformation is a history-info header (HIH) included in the SIP INVITE,the HIH generated by a network node comprising at least one of a mobileswitching center (MSC), a MSC server (MSS), or a telephony applicationserver (TAS).
 17. The system of claim 16, wherein the determinationmodule is further configured to, upon determining that the HIH ispresent in the SIP INVITE: determine whether a visited network addressof the UE is a home global title address of the UE; and determining thatthe UE is in home network of the UE based on the visited network addressof the UE; and wherein the prevention module is further configured toprevent the unanswered call from depositing a voicemail based at leastin part on a determination that the visited network address is not thehome global title address.
 18. The system of claim 17, wherein thedetermination module is further configured to determine whether thevisited network address of the UE is the home global title address of asubscriber associated with the UE based at least in part on an inquiry;and wherein the communication module is further configured to send theinquiry to one of a home location register (HLR), a home subscriberserver (HSS), or a unified subscriber database (USD).
 19. The system ofclaim 18, wherein the inquiry includes at least one of a send routinginformation (SRI) or an SRI for short message (SRI-SM).
 20. The systemof claim 17, wherein the plurality of modules further comprises arandomizer module, the randomizer module configured to: announce a setof numbers to a caller of the unanswered call; request the caller toenter a sequence of numbers from the announced set of numbers; determinewhether the caller has correctly entered the sequence of numbers; andprevent the unanswered call from depositing a voicemail upon determiningthat the caller failed to enter the sequence of numbers correctly.